Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already cover readOnly/idempotent/non-destructive, so the bar is lower, and the description still adds real behavior: a fallback to BR with `source: "fallback"` when no edge detection occurs, plus what `detected` reports. This goes beyond the annotations by disclosing return-field semantics, though other possible `source` values remain unexplained.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two compact sentences, front-loaded with the core purpose before the fallback detail. Nothing is wasted, though the brevity borders on cryptic for a reader unfamiliar with the domain's `source`/`detected` vocabulary.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema and no parameters, the description carries the full burden of explaining returns, and it only partially does so: it names `source` and `detected` but only one enum value ('fallback') and omits the rest of the response shape. Adequate for a trivial zero-arg read, but incomplete.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The tool takes zero parameters, which sets the baseline at 4. There is no argument syntax or filtering to document, so nothing is missing on this dimension.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description states the resource concretely: suggested country and language for the caller. The vague name 'geo' is rescued by 'País e idioma sugeridos', but the description never distinguishes this from siblings like list_countries or list_languages, so it stops short of a 5.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

There is no when-to-use guidance, no prerequisites, and no mention of alternatives such as list_countries/list_languages. Usage is only implied by the phrase 'para quem está chamando' (for the caller), leaving the agent to infer the trigger.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.